Pixiewps is a tool used for offline brute forcing of WPS pins. It dramatically speeds up the WPS brute force attack time from what was taking up to 12 hours to a a few seconds by exploiting the low or non-existing entropy of some wireless access points. It’s based on the pixie dust attack, discovered by Dominique Bongard (slides and video). Notes on how to install it are in the video below, if you are using Kali Linux then just apt-get update && apt-get upgrade.